Question 870789
Those being how you find you definition of a failed function, be aware of this:


A relation which has more than one value of output for any single value of input would fit your definition of a failed function.  A circle equation would be a failed function, but a circle is also two separate functions put together.  A vertical line, like any x=k for a constant k is a failed function.  Giving help for a "word problem" is not so easy.  Can you find or imagine an example of a situation or application that would be represented as a circle?    You may be able to find such an application problem in your textbook.